--> --> ABSTRACT: Coalbed Methane Resource of the Rock Springs Formation on the Rock Springs Uplift, Sweetwater County, Wyoming, by Woodruff Leel, Charles Wickstrom; #91002 (1990).

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ABSTRACT: Coalbed Methane Resource of the Rock Springs Formation on the Rock Springs Uplift, Sweetwater County, Wyoming

Woodruff Leel, Charles Wickstrom

The coal measures of the Upper Cretaceous Rock Springs Formation, member of the Mesaverde Group on the Rock Springs Uplift have a gas-in-place reserve of 9.38 tcf and a potential recoverable reserve of 6.10 tcf. The Triton Oil and Gas Corporation (TOG) #2UPRC1 (#2-1) Well, Sec. 1, T22N, R102W, Wyoming, is the first coalbed methane producer on the uplift. Gas desorption values for drill cuttings from this well range from 143 to 527 Scf/ton at depths up to 4399 ft. Fifty feet of coal, >=2 ft thick and <=1.75 g/cc, have a weighted/ foot average of 400 Scf/ton. The 50 ft isopach has an aerial extent of 12 townships.

Structurally high areas of the uplift have undergone a natural desorption process. The TOG #1UPRC-9 (#1-9) well, Sec. 9, T22N, R102W, with the top of the Rock Springs at an elevation of +5302, has gas content ranging from 0 to 130 Scf/ton for the same rank coal as the #2-1 which, at +4020, is 1282 ft structurally low to the #1-9.

Water salinity can be used as an exploration tool to determine which coals have been naturally desorbed. The presence of fresh water, 590 ppm cl., in the coal measures of the # 1-9 indicate meteoric replacement of the conate waters, 18,000 ppm cl., found in the #2-1 well. During the replacement process the hydrostatic pressure was lowered to allow natural desorption.

The new gas content and production data confirm earlier published estimates of at least 30 tcf gas-in-place of coalbed methane in the Greater Green River Coal Region.

AAPG Search and Discovery Article #91002©1990 AAPG Rocky Mountain Section Meeting, Denver, Colorado, September 16-19, 1990